The present invention relates to installation tools for setting pull type fasteners.
Installation tools and related nose assemblies are utilized in conjunction with a hydraulic pressure source for installing multi-pieced fasteners by applying a relative axial pulling force, for example, between a pin or mandrel and a collar or sleeve. A lockbolt or swage type fastener is an example of a multi-piece fastener that has a pin and collar adapted to be set with the relative axial pulling force of an installation tool. A blind type fastener is another example of a multi-piece fastener that has a pin and a sleeve adapted to be set with the relative axial pulling force of an installation tool. With both the lockbolt and blind type fasteners, the pin has an elongated shank provided with a pintail or pull portion having a plurality of pull grooves adapted to be gripped by a plurality of chuck jaws in the nose assembly. In the deactuated condition, the chuck jaws will be normally held open to facilitate insertion of the pintail portion into the aperture defined by the opened chuck jaws as well as ejection after the fastener has been set. During actuation of the tool with the pintail portion located in the nose assembly, the chuck jaws will be moved to a closed condition for engagement with the pull grooves whereby the pull grooves will be gripped by the chuck jaws.
A swage anvil member is adapted to engage the collar or sleeve, depending upon the type of fastener, and, upon actuation of the tool and with the chuck jaws gripping the pintail portion of the pin shank, as noted, a relative axial pulling force is then applied between the collar or sleeve and pin of the fastener by way of the relative axial force between the chuck jaws and the anvil. Typically, the pin or mandrel is provided with a weakened portion or breakneck groove which is located on the pin shank between the pull or pintail portion and the remainder of the shank and is adapted to fracture at a preselected axial load, i.e. pin break load, after the fastener has been set. This results in an installed fastener having a generally flush structure with minimal or no pintail protrusion. In certain tools, the severed pintail portion is ejected rearwardly out through the back end of the tool.
The magnitude of the pin break load required to fracture the breakneck groove, however, can result in the generation of a reaction load of significant magnitude. The magnitude of pin break load can be especially high with swage type fasteners since the breakneck groove must be of sufficient strength to withstand the high installation loads required for the anvil to swage the collar onto the pin. As a result, in hand held installation tools employing a construction for pass through or rearward ejection, the severed pintail portion could be ejected with a considerable force in the direction of the operator. As a result, it has been a common practice with such tools to utilize a pintail deflector made of an elastomeric material to absorb some of the force of the pintail portion and to deflect the pintail portion away from the operator.
In certain aerospace applications, a limited amount of space is provided for fastening workpieces together with a fastener. In such applications or other applications with a limited amount of space, it is necessary for an operator to have a compact installation tool with a minimal center line to edge distance in order for the operator to be able to fasten the workpieces together in these hard to reach locations. Center line to edge distance refers to the distance from the center of the bore of the installation tool that has a nose assembly disposed therein to the top edge of the installation tool. A need exists in the art these types of compact installation tools.
Additionally, in areas of limited clearance space, installation tools are typically operated at high pressure. Unfortunately, at high pressure, hydraulic hoses attached to the installation tool become rigid and limit the range of movement that an operator has with the installation tool. At lower pressures, hydraulic hoses are more flexible and extends the range of movement that an operator has with the installation tool. A need exists in the art for compact installation tools that operate at lower pressure to facilitate a greater range of movement with the installation tool.
It is an object of the invention to provide an installation tool that can be used in applications that provide a limited amount of space to an operator of the tool.
It is an additional object of the invention to provide an installation tool that is compact and has a minimal center line to edge distance.
It is another object of the invention to provide an installation tool that operates at lower pressures with flexible hydraulic hoses.
These and other objects of the invention are achieved by providing a hydraulic installation tool for installing fasteners, that includes a housing having a first portion adapted to receive a drawbar and a second portion adapted to receive a piston, a gland and a retaining ring. The drawbar has a general L-shape, a through bore and a bore. A portion of the drawbar is slidably disposed within the first portion of the housing. The piston has a threaded bore and a portion of the piston is slidably disposed within the second portion of the housing. The gland has a first bore adapted to receive a portion of the piston and the gland is disposed within the second portion of the housing with a portion of the piston passing through the bore of the gland. The gland also has a threaded second bore that is adapted to receive a threaded screw. The retaining ring has a bore and the retaining ring is disposed within the second portion of the housing and threadedly engages the housing with a portion of the piston passing through the bore of the retaining ring. A threaded first screw passes through the bore of the drawbar and threadedly engages the threaded bore of the piston and a threaded second screw passes through the bore of the retaining ring and threadedly engages the threaded second bore of the gland.